If I can offer a different opinion on that 590.
Everything from the trigger back on that shotgun is just there to lure a certain kind of buyer. It's like chrome on a truck or stripes on a car. It looks but has no function.
The adjustable stock is a good idea for mass issue of a weapon to many people of different sizes. It's nice to let it out one notch when your body armor is off. For a personally owned weapon it makes less sense than getting a standard stock and fitting to the firer. Call it more simple.
A pistol grip has pros and cons. It is better for recoil management IF the firer actually applies proper technique. It is said that it helps with pointing but I've never seen proof. Mostly, that pistol grip just gets in the way. On a Mossberg it just gets your digits further from the safety and slide release. The grip gets in the way during speed reloads too.
Giving a 12 ga to the wife. I won't give a 12 ga to mine because a shotgun is a specialty weapon, not an amateurs weapon. Indoors it is easy to miss with, slow to recover from, and the blast makes you dizzy. Reduced Recoil buckshot was the best thing invented for shotguns, ignoring M1030's.
I'd giver her a Youth Model 20 ga pump maybe. A hammerless doube might be better. The intruder won't know the difference long enough to object.